Do you want to hide add to cart if customer is not logged in?
– Rahul Kumar DasJun 9 '15 at 10:14

If you click the Cart button on any product trevorsorbie.com/shop/ranges.html nothing is added to cart. If you log in to your account and click that button it does add to cart. I'm trying to work out why it is not working on that page.
– Conor CussellJun 9 '15 at 10:18

It's not in helper, it could be in phtml files. Follow the link I given in answer, check the addtocart.phtml file
– Rahul Kumar DasJun 9 '15 at 10:20